import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

//封装针对博客表的相关操作
public class BlogDao {
    //1.插入一个博客到数据库中
    public void insert(Blog blog){
        Connection connection=null;
        PreparedStatement statement=null;
        try {
            //1.和数据库建立连接
            connection = DBUtil.getConnection();
            //2.构造sql
            String sql="insert into blog values(null,?,?,now(),?)";
            statement=connection.prepareStatement(sql);
            statement.setString(1,blog.getTitle());
            statement.setString(2,blog.getContent());
            statement.setInt(3,blog.getUserId());
            //3.执行sql
            int ret=statement.executeUpdate();
            if(ret!=1){
                System.out.println("博客插入失败");
            }else{
                System.out.println("博客插入成功");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            //4.释放对应的资源
            DBUtil.close(connection,statement,null);
        }

    }
    //2.根据博客ID来查询指定博客
    public Blog selectOne(int blogId){
        Connection connection=null;
        PreparedStatement statement=null;
        ResultSet resultSet=null;
        try{
            //1.和数据库建立连接
            connection=DBUtil.getConnection();
            //2.构造sql
            String sql="select * from blog where blogId=?";
            statement=connection.prepareStatement(sql);
            statement.setInt(1,blogId);
            //3.执行sql
            resultSet=statement.executeQuery();
            //4.遍历结果集合
            if(resultSet.next()){
                Blog blog=new Blog();
                blog.setBlogId(resultSet.getInt("blogId"));
                blog.setTitle(resultSet.getString("title"));
                blog.setContent(resultSet.getString("content"));
                blog.setPostTime(resultSet.getTimestamp("postTime"));
                blog.setUserId(resultSet.getInt("userId"));
                return blog;
            }
        }catch (SQLException e){
            e.printStackTrace();
        }finally {
            DBUtil.close(connection,statement,resultSet);
        }
        return null;
    }
    //3.直接查询博客列表
    public List<Blog> selectAll() {
        List<Blog> blogs = new ArrayList<>();

        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            //1.和数据库建立连接
            connection = DBUtil.getConnection();
            //2.构造sql
            String sql = "select * from blog order by postTime desc";
            statement = connection.prepareStatement(sql);
            //3.执行sql
            resultSet = statement.executeQuery();
            //4.遍历结果集合
            while(resultSet.next()) {
                Blog blog = new Blog();
                blog.setBlogId(resultSet.getInt("blogId"));
                blog.setTitle(resultSet.getString("title"));
                String content=resultSet.getString("content");
                if(content.length()>100){
                    content=content.substring(0,100)+".....";
                }
                blog.setContent(content);
                blog.setPostTime(resultSet.getTimestamp("postTime"));
                blog.setUserId(resultSet.getInt("userId"));
                blogs.add(blog);
            }
        }catch (SQLException e){
            e.printStackTrace();
        }finally {
            DBUtil.close(connection,statement,resultSet);
        }
        return blogs;
    }
    //4.删除指定博客
    public void delete(int blogId){
        Connection connection=null;
        PreparedStatement statement=null;
        try{
            //1.和数据库建立连接
            connection=DBUtil.getConnection();
            //2.构造sql
            String sql="delete from blog where blogId=?";
            statement=connection.prepareStatement(sql);
            statement.setInt(1,blogId);
            //3.执行sql
            int result = statement.executeUpdate();
            //4.遍历结果集合
            if(result!=1){
                System.out.println("博客删除失败");
            }else{
                System.out.println("博客删除成功");
            }
        }catch (SQLException e){
            e.printStackTrace();
        }finally {
            DBUtil.close(connection,statement,null);
        }
        return;
    }
}
